Tests

Remove Julia v1.9 get_extension compatibility code #169

Job	Run time
Tests (lts, Core) / Tests - Core	3m 2s
Tests (1, Core) / Tests - Core	5m 11s
Tests (pre, Downstream) / Tests - Downstream	5m 11s
Tests (pre, Core) / Tests - Core	2m 36s
Tests (1, Downstream) / Tests - Downstream	5m 11s
Tests (lts, Downstream) / Tests - Downstream	1s
	21m 12s

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